1. Technical Field
The present invention relates to a signal generating apparatus and a test apparatus.
2. Related Art
A signal generating apparatus is known that outputs an analog signal corresponding to data supplied thereto. When the signal output from the signal generating apparatus is supplied to a target circuit via an analog circuit such as a filter, the analog circuit causes distortion, attenuation, and the like. By outputting a signal in which the distortion and attenuation caused by the analog circuit is compensated for in advance, the signal generating apparatus can supply the target circuit with a signal having the desired level.
However, the amount of distortion and attenuation caused by the analog circuit changes according to the environment during signal generation. If the output signal of the analog circuit is measured in the background using an AD converter or the like during signal generation, the signal generating apparatus can perform accurate compensation that follows the fluctuation in the distortion and attenuation amounts of the analog circuit. Providing the signal generating apparatus with an AD converter that is separate from the signal generating functions, however, results in a larger structure and a higher cost.    Patent Document 1: U.S. Pat. No. 5,659,312    Patent Document 2: U.S. Pat. No. 5,153,592    Patent Document 3: Japanese Patent No. 3382818    Patent Document 4: U.S. Pat. No. 6,549,150